The present invention pertains to a switch which releases connections according to a connection""s priority when a predetermined condition exists in the switch. More specifically, the present invention pertains to a switch which releases connections according to a connection""s priority when an overload condition exists in the switch.
Current call admission control (CAC) algorithms generally are based only on traffic characteristics specified by a user. However, for most connections, it is very difficult to predict the nature of traffic accurately. Typically, the traffic characteristics of such connections are either over- or under-estimated. Let us consider the impact on overall link utilization while relying on traffic characteristics specified by user. Under-estimation of traffic can lead to excess traffic to link. However, with policing/shaping of traffic at the user network interface (UNI), this situation is avoided. Over-estimation, on the other hand, can lead to the resultant traffic being lower than expected leading to under-utilization of link bandwidth.
High-speed fast-packet-switched network architectures are capable of supporting a wide range of connections with different bandwidth requirements and traffic characteristics. Providing quality of service (QoS) in networks in terms of delay and bandwidth requires provisioning of network resources. While this environment provides increased flexibility in supporting various services, its dynamic nature poses difficult traffic control problems when trying to achieve efficient use of network resources. One such problem is the issue of bandwidth management and allocation. Due to the statistical multiplexing of all connections at the physical layer and the varying transmission rates by connections, it is important to characterize, both the effective bandwidth of a single connection and several multiplexed connections. Such characterization can be used to compute metrics for efficient bandwidth management, routing, and call control procedures. Based on statistical characteristics and desired grade of service, researchers in R. Guerin, H. Ahmadi, and M. Naghshineh. Equivalent capacity and its application to bandwidth allocation in high-speed networks. IEEE Journal on Selected Areas in Communication, 9(7):968-981, September 1991, incorporated by reference herein, have proposed approximate expressions for effective bandwidth or equivalent capacity computations.
A CAC algorithm based on a metric of effective bandwidth, can be summarized as follows. At any given time a new connection is admitted if:
xe2x80x83Bceff+Bleffxe2x89xa6Blink,xe2x80x83xe2x80x83(1)
where, Bceff denotes the effective bandwidth of new connection, Bleff denotes the effective bandwidth of aggregate traffic on a link, and Blink denotes the maximum link capacity or line rate. If the connection is admitted, the effective bandwidth of link is updated as, Bleff+Bceff=Bleff, otherwise it remains unchanged. Similarly, a tear-down of an established connection results in link effective bandwidth being decremented by the effective bandwidth of torn-down connection.
While the above approach is simple, it relies on the user/network being able to predetermine the traffic characteristics of a connection. However, for most connections, it is very difficult to predict the nature of traffic accurately. Typically, the traffic characteristics of such connections are either over or under-estimated. Let us consider the impact on overall link utilization while relying on traffic characteristics specified by user. Under-estimation of traffic can lead to excess traffic to link. However, with policing/shaping of traffic at the user network interface (UNI), this situation is avoided. Over-estimation, on the other hand, can lead to the resultant traffic being lower than expected leading to under-utilization of link bandwidth.
The present invention provides a dynamic CAC to overcome the problem of under-utilization of link bandwidth. The scheme, using periodic measurements, keeps track of various utilization parameters. These include the current link utilization, the variation in link utilization, buffer occupancy, and rate of change of buffer occupancy. Based on the above measurements a dynamic estimate of the effective bandwidth of the aggregate traffic on link is computed and admittance of new calls judged based on this.
The present invention pertains to a switch for a network. The switch comprises an input port mechanism which receives traffic of connections from the network. Each connection has a priority. The switch comprises an output port mechanism which sends traffic of connections to the network. The switch comprises a controller which serves connections and which monitors the connections received by the input port mechanism and sent by the output port mechanism and releases connections according to a connection""s priority when a predetermined condition exists in the switch. The controller is connected to the input port mechanism and the output port mechanism. Each connection requests a specific bandwidth from the controller.
The present invention pertains to a method for switching connections. The method comprises the steps of monitoring traffic of connections received by a switch. Then there is the step of releasing connections from the switch according to the connection""s priority when a predetermined condition in the switch exists.
The present invention pertains to a switch for a network. The switch comprises an input port mechanism which receives traffic of connections from the network. The switch comprises an output port mechanism which sends traffic of connections to the network. The switch comprises a controller which provides service to traffic of connections received at the input port mechanism and which are to be sent out the output port mechanism. The controller monitoring the traffic of connections received by the input port mechanism and sent out the output port mechanism and adjusting the service provided to the connections based on the traffic of connections received by the input port mechanism and sent out the output port mechanism. The controller is connected to the input port mechanism and the output port mechanism.
The present invention pertains to a switch for a network. The switch comprises an input port mechanism which receives cells of connections from the network. The switch comprises an output port mechanism which sends cells of connections to the network. The switch comprises a buffer mechanism for storing cells. The buffer mechanism is connected to the input port mechanism and the output port mechanism. The switch comprises a controller which provides service to traffic of connections received at the input port mechanism and which are to be sent out the output port mechanism. The controller monitors the change in the number of cells in the buffer mechanism and adjusts the service provided to the connections based on the change in the number of cells in the buffer mechanism. The controller is connected to the buffer mechanism.
The present invention pertains to a method for switching connections by a switch of a network. The method comprises the steps of monitoring the traffic of connections received by the switch and sent out the switch. Then there is the step of adjusting the service provided to the connections by the switch based on the traffic of connections received by the switch and sent out the switch.